I didn't know much about it, so I googled a little bit:
Robert Strandh is also the author of McCLIM, the free implementation of the Common Lisp Interface Manager. [1]
I found this to be interesting: "So, one example that appears to baffle people is that SICL LOOP uses LOOP for its implementation. But there is no contradiction here, because the LOOP macroexpander runs at, well, macroexpansion time, which will happen in the host Common Lisp system during bootstrapping. After that, there is no trace of the LOOP macro." [2]
